This invention relates to a circuit breaker, and more particularly, to a mechanism for moving and supporting a circuit breaker relative to a bus bar arrangement.
In many applications, a circuit interrupting device is removably connected to the primary terminals of the bus bar arrangement of a power distribution system. For example, U.S. Pat. No. 4,612,429 illustrates circuit interrupter units which are movably mounted on wheels and retractable rails so that the units can be pulled out of a metal enclosure for servicing or inspection. The circuit interrupter units are electrically connected to three-phase terminals disposed to make electrical contact with primary terminals in the rear of the metal enclosure when the circuit interrupter units are pushed into the metal enclosure and firmly seated in their normal operating positions.
One problem with this type of arrangement is supplying the force necessary to firmly seat the circuit interrupter (three-phase) terminals with the primary terminals. Additionally, a source of removal force is required to overcome the friction between interrupter terminals and the primary terminals so that the circuit interrupting devices can be retracted from the metal enclosure. One way of supplying these forces has been to use a lead screw assembly which moves the circuit interrupter along the rails when the lead screw is rotated.
Another problem with this type of arrangement is the provision of a mechanism which prevents a circuit interrupter from being disengaged from the primary terminals while the circuit interrupter is closed (un-tripped status). Another related problem is insuring that the circuit interrupter is tripped before engaging the circuit interrupter with the primary terminal.
Accordingly, it would be advantageous to provide a mechanism which can supply the forces necessary to move a circuit beaker in and out of engagement with the primary terminals of a bus bar structure. It would also be advantageous to provide a mechanism which prevents the movement of the circuit breaker when its status is un-tripped.